The invention relates to a writing instrument, which is formed as a pushbutton writing instrument and has a writing instrument housing, with a writing tip protruding beyond one end of said housing, which writing tip can be moved by means of a pushing mechanism between a writing position, projecting beyond one end of the writing instrument housing, and a standby position, located in the housing interior of the writing instrument housing, the pushing mechanism being able to be actuated by means of a pushbutton intended as a functional element, which is provided at the end of the writing instrument housing that is remote from the writing tip and which has a first pushbutton subregion, which is in drive connection with the pushing mechanism and to which a second pushbutton subregion can be detachably fastened.
DE 202 01 024 U1 already discloses a writing instrument having a writing instrument housing, which comprises two housing parts connected to each other. Integrated in the housing part that is remote from the writing tip is a machine-readable data memory, the interface device of which that is intended for connecting to an external data processing system and is designed as a USB interface is arranged in a protected manner in the connecting region of the two housing parts. In order to connect the data memory to the external data processing system, it is necessary to dismantle the writing instrument housing into its two housing parts and expose the USB interface provided on the one housing part. However, it is disadvantageous that, after dismantling the writing instrument housing, the remaining housing part with the writing tip can scarcely continue to be used as intended as a writing instrument; the previously known writing instrument is therefore only able to be used either as a writing instrument, with the writing instrument housing assembled, or as a machine-readable data memory, whereas the two functions are not available at the same time.
U.S. Pat. No. 6,773,192 B1 also already discloses a writing instrument having a writing instrument housing, which has a machine-readable data memory in its housing interior. For this purpose, the writing instrument housing is divided into two housing halves, which can be screwed together at their mutually facing ends. The data memory protrudes with its data memory connection beyond the end of the first housing half that is remote from a clip of the writing instrument, while the other, second housing half has at its end remote from the writing tip an inner cavity, into which the data memory connection protruding from the first housing half can extend in the screwed-together state of the writing instrument housing. In order to be able to use the data memory and connect its data memory connection to a data processing system, it is necessary to unscrew the housing halves and expose the data memory connection. However, it is disadvantageous that, when the writing instrument housing is unscrewed, the previously known writing instrument is temporarily scarcely available as a writing instrument in any meaningful way until the data storage operation can be completed. Since the writing instrument housing of the previously known writing instrument is divided into two housing halves, the housing half having the writing tip is too short to offer the user the required writing comfort.
DE 20 2008 017 711 U1 already discloses a writing instrument having a writing instrument housing, detachably fastened to which is a clip which contains a machine-readable data memory. In order to be able to use this machine-readable data memory in connection with an external data processing system, all that is required is to detach the clip from the writing instrument housing. The writing instrument previously known from DE 20 2008 017 711 U1 does offer the advantage that it can be used as a writing instrument while the data memory detachably held on it can also be used at the same time. However, the writing instrument can no longer be secured with the aid of the clip in the accustomed way to prevent loss if it is intended for the data memory to continue being used.
DE 33 19 994 A1 already describes a writing instrument which is designed as a pushbutton pencil. The previously known pushbutton pencil has a writing instrument housing, with a writing tip protruding beyond the end of said housing, which writing tip can be moved by means of a pushing mechanism between a writing position, projecting beyond one end of the writing instrument housing, and a standby position, located in the housing interior. The pushing mechanism can be actuated by means of a pushbutton intended as a functional element, which is provided at the end of the writing instrument housing that is remote from the writing tip. The pushbutton has a first pushbutton subregion, which is in drive connection with the pushing mechanism and carries an eraser. In order to protect the eraser while the previously known pushbutton pencil is being transported, a second pushbutton subregion is provided, given the form of a cap and able to be detachably fastened to the first pushbutton subregion in such a way that, in its position connected to the first pushbutton subregion, the second pushbutton subregion accommodates the eraser within it.
In the case of the pushbutton pencil previously known from DE 33 19 994 A1, the function of the second pushbutton subregion is restricted to covering the eraser in a protective manner in the position in which it is connected to the first pushbutton subregion, the eraser, which offers the user an additional significant function, remaining constantly connected to the first pushbutton subregion, and consequently to the writing instrument itself. During use, the user must therefore decide whether he either wishes to write with the writing tip or instead correct the writing with the eraser provided at the opposite end. Accommodating a data memory is not mentioned in DE 33 19 994 A1, let alone provided.